How to enter triplets

Make sure you set the display quantization to a triplet value. You can
set the display quantization from the Display Bar, Display Track or Display
Score dialogs. If your display quantization is not set to a triplet value,
triplets won't be properly displayed. Similarly, if your display quantization
is set to a value greater than the durations you are trying to display,
these smaller durations won't be displayed properly.

Select the duration you want by clicking on it in the durations palette
and then select triplet as the duration qualifier by clicking once on
the duration qualifier (the button to the right of the durations palette
in the main control area).

To put a triplet bracket over the figure, click on the Symbols Button,
go to Adjust and select the bracket symbol. Draw it in over the figure
and adjust it using the control points. Enter a number by using the +
and - keys on your computer keyboard. When it looks the way
you want it to, press the ENTER key. To cancel the operation press ESCAPE.